The Common Asparagus Beetle

(Crioceris asparagi) This beetle is by far the most important enemy of the asparagus plant. It was first noticed in this country at Astoria, L. I., now a part of New York City, in 1859, but its actual introduction into that locality occurred about



1856. The injury inflicted by this insect is due to the work of both adults and larvae upon the tender shoots, which they render unfit for market, early in the season. Later they destroy, by defoliation, growing plants, and are particularly injurious to seedlings, the roots of which are weakened by having their tops devoured. Larvae, as well as beetles, attack the tenderest portions of the plants, but the latter gnaw with seemingly equal relish the epidermis, or rind, of the stems. The beetles are also accused of gnawing young shoots beneath the surface, causing them to become woody and crooked in growth. The beetle illustrated in Fig. 42 is a most beautiful creature--from the entomologist's point of view--slender and graceful in form, blue-black in color, with red thorax and lemon-yellow and dark blue elytra or wing covers, with reddish border. Its length is a trifle less than one-fourth of an inch. From the scene of its first colonization in Queen's County, N. Y., the insect migrated to the other truck-growing portions of Long Island. It soon reached southern Connecticut, and has now extended its range northward through Massachusetts to New Hampshire. Southward it has traveled through New Jersey, where it was first noticed in 1868, to southern Virginia. At present it is well established in the principal asparagus-growing sections of New England, of New Jersey, Delaware, and Maryland, and is present in Pennsylvania, New York, and Ohio. The question of distribution is an important one, as this species is rapidly extending its range. In a very few years we may expect its spread to other portions of the States in which it is now local, and later it will naturally move westward to Indiana and other States west and south of there. The insect passes the winter in the beetle state under convenient shelter, and toward the end of April or early in May, according to locality, or at the season for cutting the asparagus for market, issues from its hibernating quarters and lays its eggs for the first brood. The eggs are deposited endwise upon the stem or foliage, and in the early spring upon the developed stalks, usually in rows of from two to six, or more. In from three to eight days the eggs hatch, the young larvae, commonly called "grubs" or "worms," presenting the appearance indicated in Fig. 42, c. They at once begin to feed, and are from ten days to a fortnight, according to Fitch and others, in attaining full growth. When full grown the larva appears as in Fig. 42, d. It is soft and fleshy, much wrinkled, and in color dark gray or olive, which usually becomes lighter and yellowish with age. The mature larva enters the earth, and here, within a little rounded, dirt-covered cocoon which it forms, the pupa state is assumed. In from five to eight or more days the adult beetle is produced, which soon issues from the ground in search of food and of a suitable place for the continuance of the species. In Fig. 43 is shown a spray of asparagus, with the common asparagus beetle in its different stages, asparagus top at the right showing eggs and injury. The duration of the life cycle is about thirty days from the time the eggs are laid until the insects attain maturity, but the time is shorter in the hotter parts of a season than in the cooler days of May or September. In the District of Columbia the eggs, in the warmest part of midsummer, develop in three days and the pupae in five days. From this it may be estimated that, in the very warmest weather, the development of the insect may be effected in about three weeks from the time the egg is laid. In colder climates and in spring and autumn the development from egg to beetle will require from four to perhaps seven weeks. In the northern range of the species, two and perhaps three broods are usually produced, and farther southward there is a possibility of at least a fourth generation. In the latitude of the District of Columbia the beetles usually disappear to enter into hibernation in the latter days of September. The common asparagus beetle has very efficient checks in the shape of predaceous insects, which prey upon its larvae and assist in preventing its undue increase. One of the most active of these predaceous insects is the spotted ladybird (Megilla maculata DeG.), represented in its several stages in the illustration (Fig. 44.) The adult of this beetle is rose-colored, with numerous black spots. The spined soldier-bug (Podisus spinosus Dal.) and the bordered soldier-bug (Stiretrus anchorado Fab.) are also useful as destroyers of asparagus beetle larvae, which they catch and kill by impaling them upon their long beaks and sucking out their juices. Certain species of wasps and small dragon-flies also prey upon the larvae. Asparagus beetles are very susceptible to sudden changes of temperature, and immense numbers of hibernating beetles are sometimes killed in winter during severe cold spells following "open" weather. Remedies.--The common asparagus beetle, under ordinary circumstances, may be held in restraint by the simplest means. Chickens and ducks are efficient destroyers of the insect, and their services are often brought into requisition for this purpose. A practice that is in high favor among prominent asparagus growers is to cut down all plants, including volunteer growth, in early spring to force the beetles to deposit their eggs upon new shoots, which are then cut every day before the eggs have time to hatch. Another measure of value consists in permitting a portion of the shoots to grow and serve as lures for the beetles. Here they may be killed with insecticides, or the plants, after they become covered with eggs, may be cut down and burned, and other shoots be allowed to grow up as decoys. One of the best and least expensive remedies against the larvae is fresh air-slacked lime dusted on the plants in the early morning while the dew is on. It quickly destroys all the grubs with which it comes in contact. The lime may be conveniently applied by means of a whisk-broom or a Paris green sifter. Even dry road dust applied in this manner will have a beneficial effect. The special merit of these insecticides is that they can be used without the least danger upon young shoots being cut for market or home use. Paris green and other arsenites, applied dry in powder, mixed with flour or plaster, or in solution, answer equally well, after cutting has ceased, and possess the advantage of destroying beetles as well as larvae. One pound of Paris green to a barrel of fine plaster makes a sufficiently strong mixture. It may be necessary to make two of these applications at intervals or as often as the larvae reappear on the plants. Powdered hellebore mixed with flour, one part to ten, or in solution of one ounce of hellebore to three gallons of water, is also very effective against the young larvae. Pyrethrum or buhach may be used in similar manner, and kerosene emulsion has been highly recommended by some experimenters. In hot weather, when the soil is dry, the larvae may be brushed or shaken from the plants so that they will drop to the heated ground, where they die, being unable to regain the shelter of the plants. Whichever methods for the destruction of this pest are adopted, unless the work be done thoroughly and with concerted action by all the growers in the section, the relief can not be permanent.

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